Manufacture of steam-boilers.



D. R. MAOBAIN.

MANUFACTURE OF STEAM BOILERS. APPLICATION 111.111) JAN. 3, 1911.

1,002,411 3, Patehted Septf5, 1911.

3 SHEETS-SHEET 1.

D. R. MAOBAIN- MANUFACTURE OF STEAM BOILERS. APPLIUATION rum) JAN 3 1911 Patentd Sept. 5, 1911.

3 SHEETS-SHEET 2.

' D. R. MAoBAIN. MANUFACTURE OF STEAM BOILERS. APPLICATION FILED JAN.3, 1911.

. 1,002,413 Patented Sept. 5,1911.

. s sums-sum a.

. I I u I s INVENTOR .its object is to DONALD B. IIAOBAIN, OF CLEVELAND, 08 10.

MANUFACTURE OF STEAK-BOILERS.

Specification 0! Letters Patent.

Patented Sept. 5, 1911.

" Application fled January 3, 1911. Serial No. 000,545.

To all whom it may concern:

Be it known that I, DONALD R. MAOBAIN, of Cleveland, .'in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in the Mannfacture of Steam-Boilers, of which lmprovement the followin is a specification.

My invention re ates to steam boilers of the class in which a plurality of tubes is inclosed within a shell or body, more particularly those of the locomotive type,and provide means whereby the detrimental action of the unequal expansion of the tubes and shell of the boiler will be effectually counteracted, and the objections resultant upon such unequal expansion be eliminated in the operation of the boiler.

To this end, my invention, generally stated, consists in a novel method of treatin boiler tube sheets and securing boiler tu es thereto, in such manner as to impose a compressive strain u on the tubes which acts in opposition to t e tensional strain 1mposed upon them in service by the expansion of the boiler shell; also, in a tubular steam boiler in which are combined two tube sheets which are sprung outwardly, but

without permanent set, in the direction of the length of the tubes, and a plurality of tube sheet, 2,

tubes, connected, at their opposlte ends, to said tube sheets.

he improvement claimed is hereinafter fully set forth.

In the accompanying drawings: Figure 1 is a vertical lon itudinal section, on the line a a of Fig. 2, t rough the shell of a steam boiler, illustratin the preliminary operation of the application of my invention; Figs. 2 and 3, transverse sections, on an enlarged scale, through the same, on the lines I) b and c 0, respectively, of Fig. 1; Fig. 4, a longitudinal central section, showing the boiler completed in accordance with my invention; and, Fig. 5, a View, in elevation, of

a tension rod.

- M invention is herein set forth as a plied in the manufacture of a steam boiler of the type which is well known in the art, and is now substantially standard in 1000- motive engines, and which comprises, as essential elements, a shell or waist, 1, a firebox, 2, at the rear end thereof, a smoke box, plurality 3, at the front end thereof, and a of fire tubes, 4, extending between and secured at their opposite ends to, a firebox at the front of the firebox,

rearof the smoke box.

The successful operation, in practical railroad service, construction above described, articularly when fitted with superheater tu s of comparatively large diameter, which are in use to a considerable extent, has been and is and a' front tube. sheet, 3, adjoining the y of locomotive boilers of the materially impaired by leakage at the joints I between the tubes and the firebox tube sheets, such leakage involvin waste of fuel, delays of trains, and loss 0% time and ex pense in frequent repairs. It has been conclusively demonstrated that, with a high firebox temperature and ra id circulation of water, the expansion of the shell of the boiler, between the tube sheets, is greater than that of the tubes, from which unequal expansion there results the exertion of tensile strain on the tubes and their connections to the tube sheets. If the tubes were, or could be, so connected to the front tube sheet as to be capable of slip ing therein, that is of moving longitudinally relative] thereto, without leakage at their joints with the sheet, the difference of expansion would be compensated without ob ectionable results, but as the tubes are rigidly connected to the front tube sheet, the tensile strain is exerted upon the tube beads at the firebox tube sheet, straining them to such an extent that upon a slight reduction of the temperature of the boiler, leaks will be caused be tween the tubes and tube sheets. As is well recognized by those familiar with the operation of locomotives, this leakage is a serious objection in service.

Inasmuch as the condition of unequal expansion of the shell and tubes, which is the cause of the leakage of the latter, by imposing tensile strain upon them, cannot be prevented, my-invention is designed to prevent its effect uponthe tubes from being injurious, by imposing upon them a counteracting strain in the opposite direction, z'. 6., one of compression, and thereby instituting a balance of forces which will eliminate the objectionable result produced in steam boilers of the ordinary construction. To this end, in the practice of sheets are, prior to the setting of the tubes thereln, sprung slightly outwardly, but without imposin upon them a permanent set, and are he (1 in this position. The tubes, except those that are temporarily omitted for the'application of the springmy invention, the tube i of-thef shell. J

ing devices, are then inserted in' the tube sheets, and secured therein by pr'osserm rolling, or expanding them in, any suitab e "known'manner. The springing'devices are,

then removed, and the remainder of the tubes inserted in their places, and secured in the tubesheets as'above described. The

I entire set. of tubeswilljthen be subjected to slight compressive strain, by reason of thepres'sure exerted upon their ends by the tendency of the outwardly sprung tube Referring to the drawings, the operations 7 above described may be readily and conven- -1ent1y performed b first exerting the requisite outward ten's' e strain upon the tube sheets b the application to, each ,of them,

beforejt e insertion-of the tubes, of a -plurality of tension rods, 5, which .fare passed through holes in the tube sheets,-in which tubes are subsequently inserted, these holes being located as near as may. be to thoseof the upper and lower rows of tubes. The

tension rods are provided with T heads, 5,

which bear. against the inner sides of the tube sheets, and are formed in two sections,

- linked oi-coupled together near the T'-h e ads,

so. that the latterma be inclined to as through theholesin t e tube sheets an set to bear against the inner sides thereof. The

opposite ends of the tension rods are screw threaded and provided with nuts, 5 which are adapted to abut against bearing plates or:v

bars, 6, fitting against the rear of the firebox, 2, and the frontring 3!, of the smoke box, 3, respectively. Thetension-rods are spaced at substantially uniform distances apart, so as to equalize, as far as racticable, the strain on the tube sheets, and by screwing up. thefinutsl, 5}, the tube sheets are sprung slightly outward1y,"'as, say about 1/16 of an inch or more, as shown in Figs.

1 and 4, but not sufficiently far to give them a permanent set.

In order to prevent the coning of. the sheets centrally between the tension rods, if such tendency should be developed, a limit rod, -7, having nuts, 7, on its ends, may be passed through holes in the tube sheets on the vertical center line of the boiler, midway between the upper and lower rows of tension rods, and the nuts, 7, screwed up to such distance apart as will limit the outward spring of the middle portions of the sheets to the degree desired.

When the tubesheets have been sprung outwardly as above described, and while they are still held in this sprung condition by the tension rods, 5, the tubes are inserted in the holes in the tube sheets which are not occupied by the tensionrods, and secured in nal flat condition. The tension rodsare then withdrawn, and tubes are fitted and secured in the holes ,in the tube sheets which had ;been occupied by them. The boiler, haviing been completed in other particulars of construction to which my invention does not frelate, is now in readlnessfor operation, and when,.u'nder the influence of sufiicientl high temperature, the expansion of the she Zexceeds that of, the tubes, the tensile strain on the latter induced by such unequal ex- ;pansion is,- as beforeexplained, counteriac'ted by the compression exerted by the elasticity .1 of the outwardly sprung tube sheets." J ,The meansherein set forth-for practicing my invention are simple and convenient, but it will be obvious that my inventionis not limited to its practice by the'application of such'specific means, as the necessary spring action of the tube sheets may be induced in any other suitable and preferred manner; It will further be apparent that my invention is applicable, without departure from its essential and characteristic principle and features,- in the manufacture of tubular steam boilers of types which are structurally gigerent from that which is herein exempl1- 11 claim as my invention-and desire to so cure by Letters Patent:

- 1. The improvement in the manufacture of steam'boilers which consists in the act of mechanicall imposing a compressive strain upon the boiler tubes which opposes the tensilestrain imposed upon them in service by the greater expansion of the boiler shell, and thereby produces a state orv condition in which said tensile strain is compensated and counteracted.

'2. Thev improvement in the manufacture of steam boilers which consists in the successive acts of springing the tube sheets out- ;wardly', but without permanent set, and thereafter mechanically imposin a com pressive strain upon the boiler tu es'by .securing their ends in the outwardly sprung tube sheets, thereby producing a state or condition in which the tensile strain upon the tubes due to the greater expansion of the shell is compensated and counteracted.

3. The improvement in the manufacture of steam boilers which consists in springing the-tube sheets outwardly by exerting mech'anically applied tension upon them, maintaining t e tube sheets in sprung condition but without permanent set, inserting and securing'a pluralityof boiler tubes in the tube ency of-the tube sheets to resume their origi-v tubes in the tube sheets, detaching the tension applying means from the tube sheets, and inserting and securing boiler tubes in the holes of the'tube sheets vacated by the detachment of the tension applying means.

he improvement in the manufacture of steam boilers which consists in springing the tube sheets outwardly by exerting tension upon a plurality of tension rods bearin on the inner sides of the tube sheetsand the outer ends of the boiler shell, respectively, inserting and securing a plurality of boiler sheets while the latter are mamtai'ned in sprung condition by the tension rods, detachin' the tension rods from the tube sheets, and inserting and securing boiler tubes in the holes of the tubeusheets.

vacated by the detachment of the tension rods. I Y

5. The improvement in the manufacture of steam boilers which consists in springing the tube sheets outwardly by exerting tension upon aplurality of tension rods bearing on the inner sides of the tube sheets and the outer ends of the boiler shell, respectively, prevent-ing coning of the middle portions of the tube sheets rod with adjusted outer bearings tube holes therein, inserting and securin .a plurality of boiler tubes in the tube sheets while the latter are maintained in sprung ,through by extending a limit condition b the tension rods, detaching the tension r0 s and limit rod from the tube sheets, and inserting and securing boiler tubes in the holes of the tube sheets vacated by the detachment of the tension rods and limit rod.

, 6. A. tubular steam boiler, the tubes of which are fi'xed in tube sheets which are sprung outwardly, but without permanent set, so as to be subject to a constant compressive strain, acting in opposition to the tensile strain imposed on t the expansion of the shell of the boiler.

7. A tubular steam boiler, the tube sheets of which are sprung outwardl in the direction of the lengthof the'tu es, so as to impose upon the tubes a constant compres sive strain in opposition to the tensile strain imposed upon them by the expansion of the boiler shell.

8. The combination, in a tubular steam boiler, of a shell, two.tube sheets which are sprung outwardly, but without permanent set, in the direction of the length Qof the tubes, and a plurality of boiler tubes'which are connected, at their opposite ends, to said tube sheets,

. DONALD R. MACBAIN. Witnesses:

W. F. onmzmcnn.

e tubes in and by. 

